阅读说明：本技术 一种交联聚乙烯绝缘b1级柔性耐火电缆 (Cross-linked polyethylene insulated B1-grade flexible fire-resistant cable ) 是由 李峰 吴福道 肖尚玉 于 2021-07-21 设计创作，主要内容包括：本发明公开了一种交联聚乙烯绝缘B1级柔性耐火电缆,该电缆的加工方法包括以下步骤：S1、圆铜线退火工作；S2、铜线绞线工作；S3、绝缘层加工；S4、填充玻璃纤维；S5、绕包处理工作,采用退火圆铜线第二类导体,正规绞合结构,多股绞合可增加导体的柔韧性,相邻层绞向相反,可提高导体结构稳定性,缆芯之间的空隙加以阻燃无卤无烟无碱的玻璃纤维进行填充,由此可减少在火焰燃烧条件下缆芯内部空气含量,降低相应燃烧温度,同时保证其玻纤带在高温火焰燃烧下的完整性,如该电缆结构有编织屏蔽层,则采用退火圆铜线进行铜丝编织,保证其屏蔽干扰性能,并在编织屏蔽层外再次进行同等材质的玻纤带绕包,确保其屏蔽结构的可靠性。(The invention discloses a crosslinked polyethylene insulated B1-grade flexible fire-resistant cable, and a processing method of the cable comprises the following steps: s1, annealing the round copper wire; s2, working the copper wire stranded wire; s3, processing an insulating layer; s4, filling glass fibers; s5, wrapping processing work, adopt annealing round copper wire second type conductor, normal transposition structure, the pliability of multiplely transposition multiplicable conductor, adjacent layer transposition is opposite, can improve conductor structure stability, the space between the cable core is filled with fire-retardant halogen-free smokeless alkali-free glass fiber, reducible cable core inside air content under the flame combustion condition from this, reduce corresponding combustion temperature, guarantee the integrality of its glass fiber tape under high temperature flame combustion simultaneously, if this cable structure has the braided shield layer, then adopt annealing round copper wire to carry out the copper wire weaving, guarantee its shielding interference performance, and carry out the glass fiber tape of equal material again outside the braided shield layer and wrap, guarantee its shielding structure' S reliability.)

1. A crosslinked polyethylene insulated flexible fire-resistant cable of grade B1, which is prepared by the following steps:

s1, annealing of the round copper wire: putting a prepared round copper wire second-type conductor into an annealing furnace, heating, preserving heat, cooling, adopting a gap type annealing treatment process, and finally annealing and discharging;

s2, working of copper strands: placing a plurality of processed copper wires in a stranding device, and stranding adjacent layers in opposite directions by adopting a multi-strand stranding mode to complete stranding of a plurality of groups of copper wires;

s3, processing of the insulating layer: combining a fire-resistant mica tape and cross-linked polyethylene in a mechanical lapping mode, and lapping to prepare an insulating layer;

s4, filling glass fiber: limiting the whole cable by adopting an external processing device (10), adding flame-retardant halogen-free smokeless alkali-free glass fiber into the cable, and pumping out air in the cable;

s5, lapping: the processed cable is wrapped, and then the copper wire braided shielding layer (6), the oxygen isolation layer (7) and the halogen-free low-smoke polyolefin sheath layer (9) are wrapped outside the wrapping in sequence to complete the preparation work of the whole cable.

2. The crosslinked polyethylene insulated B1-grade flexible fire-resistant cable according to claim 1, which comprises a whole body, and is characterized in that a plurality of groups of conductors (1) are arranged inside the whole body, the outer annular surface of each conductor (1) is wrapped with a fire-resistant mica tape wrapping layer (2), the outer annular surface of each fire-resistant mica tape wrapping layer (2) is wrapped with an XLPE insulating layer (3), the gaps between the conductors (1) inside the whole body are filled with glass fiber rope filling layers (4), the outer surfaces of the conductors (1) and the glass fiber rope filling layers (4) are wrapped with first glass fiber tape wrapping layers (5), the outer end surfaces of the first glass fiber tape wrapping layers (5) are wrapped with copper wire braided shielding layers (6), the outer surfaces of the copper wire braided shielding layers (6) are wrapped with oxygen isolating layers (7), and the outer surfaces of the oxygen isolating layers (7) are wrapped with second glass fiber tape layers (8), and the outer surface of the second glass fiber tape wrapping layer (8) is wrapped with a halogen-free low-smoke polyolefin sheath layer (9).

3. The flexible fire-resistant cable with crosslinked polyethylene insulation grade B1 as claimed in claim 2, wherein the overlap ratio of the sheath layer (9) is not less than 15% of the bandwidth.

4. The crosslinked polyethylene insulated B1-grade flexible fire-resistant cable according to claim 2, wherein the halogen-free low-smoke polyolefin sheath layer (9) is provided with an armor layer on the outer surface, the inside of the armor layer is wrapped by high-strength galvanized steel strip gap type double steel strip, the steel strip gap is not more than 50% of the width, the dielectric strength of the armor layer is not less than 40KV/mm, and the volume resistivity is not less than 2 x 10¹⁸Ω×m。

5. The crosslinked polyethylene insulated B1-grade flexible fire-resistant cable according to claim 2, wherein the copper wire braided shielding layer (6) is braided with an annealed round copper wire, and glass fiber tape wrapping of the same material is performed again outside the braided shielding layer.

6. The crosslinked polyethylene insulation B1-grade flexible fire-resistant cable according to claim 2, wherein the halogen-free low-smoke polyolefin sheath layer (9) has a dielectric strength of 25MV/m or more and a volume resistivity of 2 x 10 or more at room temperature¹²Ω×m。

7. The crosslinked polyethylene insulated B1-grade flexible fire-resistant cable as claimed in claim 1, wherein the temperature is raised to 500-600 ℃ in step S1, the temperature is maintained for 1-1.5h, and then the cable is cooled for 1-2 h.

8. The crosslinked polyethylene insulated flexible fire-resistant cable of grade B1 according to claim 1, wherein the step S2 is a concentric twisting manner.

9. The crosslinked polyethylene insulated flexible fire-resistant cable of grade B1 as claimed in claim 1, wherein the glass fiber is in the form of ribbon in step S4.

Technical Field

The invention relates to a cable, in particular to a crosslinked polyethylene insulated B1-grade flexible fire-resistant cable, and belongs to the technical field of B1-grade flexible fire-resistant cable application.

Background

Important public places such as large-scale meeting places, office buildings, hotels, hospitals, subway stations and the like have certain power supply requirements under the condition of fire disasters, normal power supply of cables and uninterrupted power supply of various control signals and alarm signals are guaranteed within a certain period of time, valuable time is provided for escape, automatic alarm, starting of fire-fighting facilities, rescue and use of emergency equipment, and people pay more attention to public building fire-fighting power distribution systems day by day. The fireproof cable is developed earlier abroad, and the fireproof cable gradually replaces the traditional B l-grade fireproof cable, so that the fireproof cable not only can be comparable to the traditional fireproof cable in the aspects of fireproof and combustion performance indexes, but also has advantages in the aspects of product specification diversity, large-scale production efficiency, installation and laying and the like.

Patent publication No. CN 212411656U's utility model discloses a high safe low release is steamed low fire-retardant flexible fireproof cable of cigarette B1 level of cigarette nothing, include: a cable core; the filling layer wraps the outer side of the cable core; the fire insulation layer is wrapped on the outer side of the filling layer and comprises at least one layer of halogen-free multilayer microcapsule-coated microcapsule red phosphorus high-flame-retardant layer; oversheath, oversheath wrap up in the layer outside of separating a fire, and the oversheath is low smoke and zero halogen ethylene-vinyl acetate copolymer sheath, the utility model provides an among the prior art technical problem that the fire-retardant incombustibility of cable is not enough.

The existing fire-resistant cable is not wrapped outside the cabling cable core in the using process, so that the cable is easy to pulverize in a high-temperature environment, meanwhile, a shielding layer is not arranged outside the cable, the shielding interference performance is poor, and a good using effect cannot be achieved when the cable is used.

Disclosure of Invention

The invention aims to provide a crosslinked polyethylene insulated B1-grade flexible fire-resistant cable, which solves the problems that the cable is easy to pulverize in a high-temperature environment because the exterior of a cabling cable core is not wrapped, and the cable is poor in interference shielding performance because a shielding layer is not arranged on the exterior and cannot achieve a good using effect when in use.

The purpose of the invention can be realized by the following technical scheme: a crosslinked polyethylene insulated flexible fire-resistant cable of grade B1 is prepared by the following steps:

s1, annealing of the round copper wire: putting a prepared round copper wire second-type conductor into an annealing furnace, heating, preserving heat, cooling, adopting a gap type annealing treatment process, and finally annealing and discharging;

s2, working of copper strands: placing a plurality of processed copper wires in a stranding device, and stranding adjacent layers in opposite directions by adopting a multi-strand stranding mode to complete stranding of a plurality of groups of copper wires;

s3, processing of the insulating layer: combining a fire-resistant mica tape and cross-linked polyethylene in a mechanical lapping mode, and lapping to prepare an insulating layer;

s4, filling glass fiber: limiting the whole cable by adopting an external processing device, adding flame-retardant halogen-free smokeless alkali-free glass fiber into the cable, and pumping out air in the cable;

s5, lapping: the cable after the processing is finished is wrapped, and then the copper wire braided shielding layer, the oxygen isolation layer and the halogen-free low-smoke polyolefin sheath layer are sequentially wrapped outside the wrapping to finish the preparation work of the whole cable.

Preferably, this insulating B1 level flexible fire resisting cable of crosslinked polyethylene includes wholly, and whole inside is provided with the multiunit conductor, conductor annular surface parcel has fire resistant mica tape around the covering, fire resistant mica tape has the XLPE insulating layer around covering annular surface parcel, and whole inside gap department that is located between the conductor all fills there is fine rope filling layer of glass, conductor and fine rope filling layer surface parcel of glass have first glass fiber tape around the covering, and first glass fiber tape has the copper wire to weave the shielding layer around the outer terminal surface parcel of covering, the copper wire is woven the shielding layer outer surface parcel and is had an oxygen layer that separates, it has second glass fiber tape around the covering to separate oxygen layer outer surface parcel, second glass fiber tape has low smoke and zero halogen polyolefin restrictive coating around the covering outer surface parcel of covering.

Preferably, the halogen-free low-smoke polyolefin sheath layer can form a compact oxygen-insulating layer under the flame combustion condition, and the overlapping rate is not less than 15% of the bandwidth.

Preferably, the outer surface of the halogen-free low-smoke polyolefin sheath layer is provided with an armor layer, the inside of the armor layer is wrapped by high-strength galvanized steel strip gap type double steel strips, the gap of the steel strips is not more than 50% of the width of the steel strips, the vibration resistance, the creep resistance, the tensile resistance, the compressive resistance and the biological resistance of the cable are improved, the dielectric strength of the armor layer is not less than 40KV/mm, and the volume resistivity is not less than 2 x 10¹⁸Ω×m。

Preferably, the copper wire braided shielding layer is braided by adopting an annealed round copper wire to ensure the shielding interference performance of the copper wire braided shielding layer, and the glass fiber tape wrapping of the same material is carried out again outside the braided shielding layer to ensure the reliability of the shielding structure.

Preferably, the halogen-free low-smoke polyolefin sheath layer has a dielectric strength of not less than 25MV/m at normal temperature and a volume resistivity of not less than 2 x 10¹²Ω×m。

Preferably, the temperature in the step S1 is raised to 500-600 ℃, the temperature is maintained for 1-1.5h, and then cooling is carried out for 1-2 h.

Preferably, the step S2 adopts a concentric twisting method.

Preferably, in the step S4, the glass fibers are in a ribbon shape.

Compared with the prior art, the invention has the beneficial effects that:

1. adopt annealing round copper wire second type conductor, regular transposition structure, the pliability of multiplely transposition multiplicable conductor, improve mechanical strength, adjacent layer transposition is opposite, can improve conductor structure stability, the space between the cable core is filled with fire-retardant halogen-free smokeless alkali-free glass fiber, it must be inseparable to require to fill, reducible inside air content of cable core under the flame combustion condition from this, reduce corresponding combustion temperature, the cabled cable core is outer to be wrapped with the glass fiber tape of equal material, guarantee the integrality of its glass fiber tape under high temperature flame combustion simultaneously, do not chalk, if this cable structure has the weaving shielding layer, then adopt annealing round copper wire to carry out the copper wire weaving, guarantee its shielding interference performance, and carry out the glass fiber tape of equal material again outside weaving the shielding layer and wrap, guarantee its shielding structure's reliability.

2. The outer layer of the glass fiber belt is directly extruded with a layer of ceramic fire-resistant halogen-free low-smoke flame-retardant polyolefin material, the ceramic polyolefin material can form a compact oxygen-isolating layer under the condition of flame combustion, so that the damage of flame to the inner structure of the cable core can be prevented, the integrity of the cable core can be ensured, and meanwhile, the volatilization of combustible gas in the cable core can be reduced, so that the corresponding combustion temperature is reduced, the glass fiber belt of the same material is wrapped outside the oxygen-isolating layer, the glass fiber belt is compact and round, the overlapping rate is not less than 15% of the bandwidth, the dripping generated due to ceramic crust of the ceramic polyolefin under the condition of flame combustion can be reduced, and the shaping ceramic of the polyolefin at the initial stage of combustion can be ensured.

3. The inside limit of processingequipment is put inside the notch of offering the confession and rotating the threaded rod activity of disc, when rotating the threaded rod and rotating, can effectively drive and press from both sides tight plectane and move inside, accomplishes the tight work of clamp to the cable, when rotating the limited threaded rod, can press from both sides tightly the injecing to the cable of placing in semicircle clamp groove inside to ensure that the cable junction is linear state, the filler of being convenient for is filled, the outside personnel's of being convenient for processing treatment work reaches better packing efficiency.

Drawings

In order to facilitate understanding for those skilled in the art, the present invention will be further described with reference to the accompanying drawings.

FIG. 1 is a schematic overall perspective view of the present invention;

FIG. 2 is a perspective view of the internal structure of the processing apparatus of the present invention;

FIG. 3 is an enlarged view of the internal structure of the area A in FIG. 2 according to the present invention;

FIG. 4 is a schematic plan view of the inner structure of the blanking tube according to the present invention;

fig. 5 is a table showing the results of the B l grade performance tests for the cable of the present invention.

In the figure: 1. a conductor; 2. a fire-resistant mica tape lapping layer; 3. an XLPE insulating layer; 4. a glass fiber rope filling layer; 5. a first glass fiber tape wrapping layer; 6. weaving a shielding layer by using copper wires; 7. an oxygen barrier layer; 8. a second glass fiber tape wrapping layer; 9. a halogen-free low-smoke polyolefin sheath layer; 10. a processing device; 101. a feed hopper; 102. a discharging pipe; 1021. a disc is arranged at the edge; 1022. a material conveying pipe is arranged inside; 1023. clamping the circular plate; 1024. rotating the threaded rod; 103. a limiting plate; 1031. a semicircular clamping groove; 1032. a disc is arranged on the upper portion; 1033. defining a threaded rod.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides three embodiments

Example 1

Referring to fig. 1 and 5, a cross-linked polyethylene insulated B1 grade flexible fire-resistant cable is prepared by the following steps:

s1, annealing of the round copper wire: putting a prepared round copper wire second-type conductor into an annealing furnace, heating to 500 ℃, preserving heat for 1h, cooling for 1h, adopting a gap type annealing treatment process, and finally annealing and discharging;

s2, working of copper strands: placing a plurality of processed copper wires in a stranding device, and stranding adjacent layers in opposite directions by adopting a multi-strand stranding mode to complete stranding of a plurality of groups of copper wires;

s3, processing of the insulating layer: combining a fire-resistant mica tape and cross-linked polyethylene in a mechanical lapping mode, and lapping to prepare an insulating layer;

s4, filling glass fiber: limiting the whole cable by adopting an external processing device 10, adding flame-retardant halogen-free smokeless alkali-free glass fiber into the cable, and pumping out air in the cable;

s5, lapping: the cable after the processing is finished is wrapped, and then the copper wire braided shielding layer 6, the oxygen isolation layer 7 and the halogen-free low-smoke polyolefin sheath layer 9 are sequentially wrapped outside the wrapping to complete the preparation work of the whole cable.

Insulating B1 level flexible fire resisting cable of crosslinked polyethylene, which comprises a whole, whole inside is provided with multiunit conductor 1, 1 annular surface parcel of conductor has fire resistant mica tape around covering 2, fire resistant mica tape has XLPE insulating layer 3 around the covering of 2 annular surfaces of covering, whole inside gap department that is located between the conductor 1 all fills there is fine rope filling layer 4 of glass, conductor 1 and fine rope filling layer 4 surface parcel of glass have first glass fiber tape around covering 5, and first glass fiber tape has copper wire to weave shielding layer 6 around the covering of 5 outer terminal surface parcels of covering, the copper wire is woven shielding layer 6 surface parcel and is had an oxygen layer 7 that separates, it has second glass fiber tape around covering 8 to separate oxygen layer 7 surface parcel, second glass fiber tape has low smoke polyolefin restrictive coating 9 around the covering 8 surface parcel of covering.

The halogen-free low-smoke polyolefin sheath layer 9 can form a compact oxygen isolation layer under the flame combustion condition, and the overlapping rate is not less than 15% of the bandwidth.

The outer surface of the halogen-free low-smoke polyolefin sheath layer 9 is provided with an armor layer, the inside of the armor layer is wrapped by high-strength galvanized steel strip gap type double steel strips, the gap of the steel strips is not more than 50% of the width of the steel strips, the vibration resistance, the creep resistance, the tensile resistance, the compressive resistance and the biological resistance of the cable are improved, the dielectric strength of the armor layer is not less than 40KV/mm, and the volume resistivity is not less than 2 multiplied by 10¹⁸Ω×m。

The copper wire braided shielding layer 6 is formed by braiding copper wires by adopting annealed round copper wires, so that the interference shielding performance of the copper wire braided shielding layer is guaranteed, and the glass fiber tapes of the same material are wrapped outside the braided shielding layer again, so that the reliability of the shielding structure is guaranteed.

The halogen-free low-smoke polyolefin sheath layer 9 has dielectric strength of more than or equal to 25MV/m at normal temperature and volume resistivity of more than or equal to 2 multiplied by 10¹²Ω×m。

In step S2, a concentric twisting method is used.

In step S4, the glass fibers are in the form of a ribbon.

Example 2

Referring to fig. 1, a cross-linked polyethylene insulated B1 grade flexible fire-resistant cable is manufactured by the following steps:

s1, annealing of the round copper wire: putting a prepared round copper wire second-type conductor into an annealing furnace, heating to 600 ℃, preserving heat for 1.5h, cooling for 2h, adopting a gap annealing treatment process, and finally annealing and discharging;

s2, working of copper strands: placing a plurality of processed copper wires in a stranding device, and stranding adjacent layers in opposite directions by adopting a multi-strand stranding mode to complete stranding of a plurality of groups of copper wires;

s3, processing of the insulating layer: combining a fire-resistant mica tape and cross-linked polyethylene in a mechanical lapping mode, and lapping to prepare an insulating layer;

s4, filling glass fiber: limiting the whole cable by adopting an external processing device 10, adding flame-retardant halogen-free smokeless alkali-free glass fiber into the cable, and pumping out air in the cable;

s5, lapping: the cable after the processing is finished is wrapped, and then the copper wire braided shielding layer 6, the oxygen isolation layer 7 and the halogen-free low-smoke polyolefin sheath layer 9 are sequentially wrapped outside the wrapping to complete the preparation work of the whole cable.

Insulating B1 level flexible fire resisting cable of crosslinked polyethylene, which comprises a whole, whole inside is provided with multiunit conductor 1, 1 annular surface parcel of conductor has fire resistant mica tape around covering 2, fire resistant mica tape has XLPE insulating layer 3 around the covering of 2 annular surfaces of covering, whole inside gap department that is located between the conductor 1 all fills there is fine rope filling layer 4 of glass, conductor 1 and fine rope filling layer 4 surface parcel of glass have first glass fiber tape around covering 5, and first glass fiber tape has copper wire to weave shielding layer 6 around the covering of 5 outer terminal surface parcels of covering, the copper wire is woven shielding layer 6 surface parcel and is had an oxygen layer 7 that separates, it has second glass fiber tape around covering 8 to separate oxygen layer 7 surface parcel, second glass fiber tape has low smoke polyolefin restrictive coating 9 around the covering 8 surface parcel of covering.

The halogen-free low-smoke polyolefin sheath layer 9 can form a compact oxygen isolation layer under the flame combustion condition, and the overlapping rate is not less than 15% of the bandwidth.

The outer surface of the halogen-free low-smoke polyolefin sheath layer 9 is provided with an armor layer, the inside of the armor layer is wrapped by high-strength galvanized steel strip gap type double steel strips, the gap of the steel strips is not more than 50% of the width of the steel strips, the vibration resistance, the creep resistance, the tensile resistance, the compressive resistance and the biological resistance of the cable are improved, the dielectric strength of the armor layer is not less than 40KV/mm, and the volume resistivity is not less than 2 multiplied by 10¹⁸Ω×m。

The copper wire braided shielding layer 6 is formed by braiding copper wires by adopting annealed round copper wires, so that the interference shielding performance of the copper wire braided shielding layer is guaranteed, and the glass fiber tapes of the same material are wrapped outside the braided shielding layer again, so that the reliability of the shielding structure is guaranteed.

The halogen-free low-smoke polyolefin sheath layer 9 has dielectric strength of more than or equal to 25MV/m at normal temperature and volume resistivity of more than or equal to 2 multiplied by 10¹²Ω×m。

In step S2, a concentric twisting method is used.

In step S4, the glass fibers are in the form of a ribbon.

Experiment of

According to the cable manufactured by the two embodiments and the cable existing in the prior art, a certain manufacturer detects the performance of various cables and performs the following tests:

correspondingly, two kinds of cables prepared by the two embodiments and one kind of cable appearing in the market are taken, three different cables are placed on the operating platform and are marked, the fire resistance inside the cable is detected through an external heating instrument, and the detection data are shown in the following table:

cable high and low temperature resistance comparison display meter

Cable with a protective layer	Existing	Example 1	Example 2
				Duration of fire resistance/min	8	27	35

From the data shown in the table, it can be seen that the fire resistance of the cables obtained by purifying the above two examples is better than that of the cables obtained by the prior art, and the fire resistance of the cables obtained by purifying the above two examples is the strongest in example 2

Example 3

Referring to fig. 2-4, a feeding hopper 101 is fixedly installed at an upper end of a processing device 10 for processing cables, a blanking tube 102 is fixedly installed at one end of the processing device 10, and a limiting plate 103 is fixedly installed at one side of the upper end of the processing device 10;

a semicircular clamping groove 1031 is formed in the middle of the upper end of the limiting plate 103, an upper disc 1032 is fixedly mounted at the upper end of the limiting plate 103, a limiting threaded rod 1033 is rotatably connected in the middle of the upper end of the upper disc 1032, an internal feed pipe 1022 is arranged at an outlet of the blanking pipe 102, edge discs 1021 are arranged at two sides of the internal feed pipe 1022 at the outlet of the blanking pipe 102, a clamping disc 1023 is movably connected in the edge disc 1021, and a rotating threaded rod 1024 is rotatably connected at the upper end of the clamping disc 1023;

the inside notch that supplies to rotate threaded rod 1024 activity of seting up of disc 1021 is put on limit, when rotating threaded rod 1024 and rotating, can effectively drive and press from both sides tight plectane 1023 and remove inside, accomplishes the tight work of clamp to the cable, when rotating injecing threaded rod 1033, can press from both sides tightly the injecing to the cable of placing in semicircle clamp groove 1031 inside to ensure that the cable junction is linear state, the stopping of being convenient for is filled.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "left", "right", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation and a specific orientation configuration and operation, and thus, should not be construed as limiting the present invention. Furthermore, "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and the like are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be directly connected or indirectly connected through an intermediate member, or they may be connected through two or more elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

While one embodiment of the present invention has been described in detail, the description is only a preferred embodiment of the present invention and should not be taken as limiting the scope of the invention. All equivalent changes and modifications made within the scope of the present invention shall fall within the scope of the present invention.